GCSE Physics: Space Physics

Space physics is a whole topic of separate (triple) GCSE Physics, for example section 4.8 of AQA's specification, and it is not part of combined science. This material covers it from the solar system to the expanding universe.

You begin with what the solar system contains: one star, eight planets, dwarf planets such as Pluto, natural satellites and artificial satellites, all within the Milky Way galaxy. You explain how the Sun formed when gravity pulled together a cloud of dust and gas, and why a main sequence star stays stable for billions of years: the inward pull of gravity is balanced by the outward pressure produced by energy from fusion.

Next come the life cycles of stars. A star about the size of the Sun becomes a red giant, then a white dwarf and finally a black dwarf. A star much more massive than the Sun becomes a red supergiant and explodes as a supernova, leaving a neutron star or a black hole. You link this to where the elements come from: fusion in stars makes elements up to iron, heavier elements are made in supernovae, and the explosion spreads them through the universe.

The orbits section explains why an object moving in a circle at constant speed is still accelerating (its direction, and so its velocity, keeps changing) and, at Higher tier, why a satellite in a smaller stable orbit has to move faster.

The final section is about red-shift. Light from distant galaxies has longer wavelengths than expected, and more distant galaxies show a greater red-shift, so they are moving away faster. This is evidence that the universe is expanding and supports the Big Bang theory. You also meet the observations of distant supernovae since 1998 suggesting that the expansion is speeding up, and the ideas of dark matter and dark energy, which scientists do not yet understand. A data question asks you to use the proportion between distance and speed of recession.

The material offers three formats. The quiz has 12 questions mixing single-answer and multiple-answer items, each with an explanation. The flashcards give quick revision of the life-cycle sequences and key definitions. The written work is a printable sheet of 8 longer questions, including full life-cycle descriptions, orbit explanations and a red-shift data analysis, which you answer by hand and upload for feedback on each answer.

• Describe the objects in the solar system and its place in the Milky Way
• Explain how stars form and why a main sequence star is stable
• Describe the life cycles of a Sun-sized star and of a much more massive star
• Explain how elements up to iron and heavier than iron are produced and distributed
• Explain why an object in a circular orbit is accelerating, and (Higher) how orbital speed depends on radius
• Use red-shift observations as evidence for an expanding universe and the Big Bang theory

Practice material written by Zestly, based on the DfE GCSE physics subject content (space physics, physics only), with AQA GCSE Physics 8463 section 4.8 used as the example specification.